Use these steps to achieve a definitive diagnosis

On a typical day in the office, a patient may present either for a follow-up for, or for an emergent complaint of red, itchy and/or irritated eyes. Considering, allergies may affect as many as 50 million people in the United States and with allergies increasing at a rate of 30% of adults and 40% of children, this makes sense.1,2 In fact, current estimates suggest at least 20% of the overall population suffers from some form of allergic conjunctivitis.2 But, how do you know that the aforementioned patient, and others like him, have allergic conjunctivitis vs. viral or bacterial conjunctivitis?

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Here, I provide the four steps that will enable you to make the correct diagnosis and, thus, get the patient the treatment(s) he needs. (See “Treatment Options for Allergic Conjunctivitis.”)


An early concept taught in my optometry training was FOLDARS, or Frequency, Onset, Location, Duration, Aggravating or Relieving factors and Severity. This simple mnemonic provides a good deal of information to flesh out the patient’s chief complaint.

For instance, after gathering the medical history from your patient, you might have a response that includes, “red, itchy, burning eyes for the last two to three weeks, that seem to be worse as the day continues, but last throughout the day. It is worse this time of year, but it hasn’t been this bad before. Placing a cold rag over my eyes helps a little, but the condition still seems to be getting worse.”

Papillary conjunctivitis can be associated with bacterial and/or allergic conjunctivitis.
Photo courtesy of Vin T. Dang,O.D., F.A.A.O.


Now, dig deeper by asking about specific symptoms. Itching, for instance, is usually the hallmark sign of some form of allergy, but other key characteristics include bilateral presentation and watery/ropy white discharge.

That said, late-onset smoldering viral conjunctivitis can also present with itching and binocular signs. The difference, however, is that symptoms start in one eye and then move to the other. As a result, asking the patient whether this was the case with his condition and receiving a, “Yes” should make you suspicious for viral conjunctivitis.

Finally, a sticky yellowish discharge is indicative of bacterial conjunctivitis.

Treatment Options for Allergic Conjunctivitis


  • Avoidance. This is the first line of defense. Of course, it is virtually impossible to avoid the outdoors, but if the patient can minimize his encounters with the offending allergen(s), he can minimize symptoms and, therefore, the need for medications.
  • High-energy particulate arresting air purifier. This tool filters out allergens from the bedroom and other rooms where there might be high traffic or carpeting that can carry and hold allergens, respectively.
  • Replace filters. Replacing home central heating and air conditioning filters with ones that filter out smaller allergens can be helpful as well. For example, I recommend 3M’s Filtrete MPR 2200, which traps small particles.3
  • Doctor’s Rx Allergy Formula (Bausch + Lomb). Before prescribing one or more of the several allergy OTC medications on the market, I will recommend this homeopathic supplement. It contains a proprietary blend of quercetin, bromelain, grape seed extract, butterbur, mirtoselect and pycnogenol. And this proprietary capsule can only be obtained via a specialty pharmacy.
    My reasoning behind using this first is that I want to prevent the desiccating effect of non-selective H2 histamine blockers, which can cause dry eye disease symptoms. The generic Claritin, Zyrtec and Allegra, as examples, all provide relief from watery and itchy eyes, but one of the major side effects of these OTC regimens is they make dry eye disease worse.
  • Topical antihistamine/mast cell stabilizer. This targeted therapy is ideal for patients who are experiencing allergic conjunctivitis symptoms sans allergic rhinitis. This is because the topical antihistamine blocks the histamine response of itching, watering and redness, and the mast cell stabilizer limits the release of histamine to help with future symptoms. Examples of this therapy: alcaftadine 0.25% (Lastacaft, Allergan); azelastine hydrochloride (Optivar, Meda Pharmaceuticals, also in generic); bepotastine besilate 1.5% (Bepreve, Bausch + Lomb); cromolyn sodium 4% (Crolom, Bausch + Lomb, also in generic); epinastine 0.05% (Elestat, Allergan; also in generic); ketotifen fumarate 0.035% (Zaditor, Alcon; also in generic); lodoxamide tromethamine 0.1% (Alomide, Novartis); nedocromil sodium 2% (Alocril, Allergan, also in generic); olopatadine 0.7%, 0.2% and 0.1% (Pazeo, Pataday and Patanol, respectively, Novartis, 0.1% in generic); and cetirizine 0.24% (Zerviate, Nicox).
  • Steroid. If the patient presents with an acute allergic conjunctivitis episode, I immediately prescribe a steroid approved for the condition, such as loteprednol etabonate 0.2% (Alrex, Bausch + Lomb) or off-label choices, such as fluorometholone or prednisolone acetate 0.12% (Pred Mild, Allergan). Flare ups come in different shapes and sizes, requiring a more potent steroid. Off-label choices: prednisolone acetate 1%, loteprednol etabonate 0.5% or gel (Lotemax, Lotemax Gel, Bausch + Lomb), difluprednate 0.05% (Durezol, Novartis) or Lotemax Gel (Bausch + Lomb).
  • Immunotherapy. When drugs aren’t enough, I suggest referring patients to an allergist who can provide allergy shots or sublingual immunotherapy. The latter provides the comfort of avoiding injections, the convenience of home self-administration and a good safety profile.


As suspicion is not the same as “guilt,” the next step is to use an array of devices and tests to help us arrive at a diagnosis:

  • Overhead lamp. I like to do a gross evaluation of the patient’s eyes with the overhead lamp. This allows me to get a holistic view to gain a greater appreciation of the clinical presentation. Sometimes, the big picture gets missed when looking only at the eye via slit lamp.
    First, I pull on the upper and lower lid to elicit a view of the palpebral conjunctiva. This enables me to differentiate between diffuse injection vs. sectoral injection, along with discharge, which is sometimes observed in the tear film. An allergic conjunctivitis presentation will be more difficult to differentiate against a pingueculitis or episcleritis.
  • Slit lamp. Careful evaluation of the conjunctival tissue, the adnexa, lids and cornea can further differentiate the type of conjunctivitis. Pay close attention to the different types of “bumps” on the palpebral conjunctiva. Raised cobblestone papillae with central vascular cores are usually associated with bacterial and allergic conjunctivitis. Remember that bacterial conjunctivitis will have a sticky, yellowish discharge. Allergic conjunctivitis typically does not, but the patient history will also help with diagnosis, especially if it’s in one eye vs. two eyes. Another feature of allergic conjunctivitis that could be observed is punctate keratopathy, due to excessive rubbing of the eyes from itching. In severe cases of allergic conjunctivitis, such as vernal keratoconjunctivitis, you may observe Horner-Trantas dots (white dots on top of large papillae along the limbus, due to eosinophilic congregation).
    Follicles, which appear as small dome-shaped nodules that have a clear center and vasculature surrounding the dome are usually associated with viral conjunctivitis, atypical bacteria, such as Chlamydia, or toxic conditions, such as a brimonidine allergy.
    Papillae commonly appear redder on their surface and pale at their base, whereas follicles are paler on their surface and redder at their base.
    Further, a smoldering, or acute, viral conjunctivitis might have sub-epithelial infiltrates.


Three point-of-care tests are now available to aid us in determining the diagnosis:

  1. AdenoPlus (Quidel). This test confirms or rules out adenoviral conjunctivitis within 10 minutes of use. (See: .)
  2. AllerFocus (AllerFocus). This is a non-invasive skin test, offering a 78-allergen sample kit, along with a positive and negative control testing bay. (See: ).
  3. DoctoRx’s Allergy (Bausch + Lomb). This too is a non-invasive skin test. It checks for 58 different environmental allergens geographically specific to a particular part of the United States, with 39 regionalized formulas, and it also includes a positive and negative control testing bay. (See .) A Caveat: If you decide to use this test, it is important to instruct the patient to cease any anti-histamines they may be self-medicating with for at least five days, so the test does not render a false negative.

These point-of-care tests will help you to narrow down the differential diagnoses. Sometimes, patients could have dry eye disease along with allergic conjunctivitis. Many times, the diagnoses can be confounded by other co-morbidities. (Consider “Is it Allergy or Dry Eye?” at .)


Many patients who present for their annual eye exams or with a persistent red eye may not think of us as sources of relief, but once we go through the four-step diagnostic process and then prescribe the right ocular allergy therapy, they’ll see our additional value in their eye care. OM


  1. Wood R, Camargo C, Lieberman P, et al. Anaphylaxis in America: the prevalence and characteristics of anaphylaxis in the United States. J Allergy Clin. Immunol. Feb 2014; 2: 461-67.
  2. American College of Allergy, Asthma, and Immunology. Allergy Facts. Accessed June 27, 2018.
  3. Filtrete Healthy Living Air Filter. Filtrete website. . Accessed June 27, 2018.

Special thanks to Jason Schmidt, O.D., for reviewing this article.